Dr. Bailey-Wilson is a member of a collaborative study of Attention Deficit Hyperactivity Disorder, collaborating with Drs. Max Muenke and Kate Berg of NHGRI and Dr. Mauricio Arcos-Burgos of NHGRI and University of Antioquia, Columbia. Dr. Bailey-Wilson's role is to help with study design and to serve as statistical geneticist on the project. In the past, we have performed power studies of many large pedigrees from Columbia, showing that there will be adequate power in a linkage study to detect genes of moderate to large effect, even in the presence of heterogeneity. Dr. Bailey-Wilson also advises the other collaborators about the types of pedigree structures that are particularly informative for linkage studies. A paper detailing the study design and the simulation has been published in this fiscal year. In this fiscal year, linkage and association studies have been performed on the first set of large pedigrees from Columbia for markers in several candidate loci. A manuscript reporting evidence of the presence of linkage and association of ADHD with the DRD4 locus in these families is in press in Molecular Psychiatry. Genome-wide scan lgenotyping has been completed at CIDR in the first set of families and inkage analysis has been completed by on these data. We are currently planning finemapping studies to further investigate the most promising regions from the genome-wide scan analysis.